Vat dye compositions



Still more particularly it relates to the preparaat between about 50 C. to 100 C. and an oxidiz- 5 Patented Sept. 19, 1939 2,173,506

UNITED STATES PATENT OFFICE VAT DYE CQMPQSI'EIONS John Elton Cole, Wilmington, Del., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application July 17, 1937, Serial No. 154,193

8 Claims. (Cl. 260-331) The present invention relates to the manufac amount of salt which is added will vary widely ture of dyestuif pastes and powders. More paralthough an amount between 0.1 of a gram to ticularly it relates to the manufacture of dyestuif 100 grams per 1000 0.0. of solution is generally pastes and powders for use in textile printing. satisfactory. The temperature is then adjusted tion of thioindigo dyes which are especially advaning agent is added. The dye is then removed by tageous in rayon printing. filtration and is standardized.

Ever since the discovery of commercial methods The preferred embodiment of this invention for the manufacture of indigo there have been comprises dissolving or suspending a thioindoxyl 10 many attempts to control the physical form of in an alkali solution, preferably sodium hydroxide. l0 vat dyes, especially the indigoid types, in order The alkalinity is preferably between about 0.5% to obtain optimum working properties. Many to about 10% of caustic soda. To this mixture attempts have been made to improve the covering is added about 1 gram of a high alkylated naphpower of the dye pigment by precipitating the thalene sulfonic acid sodium salt.' The tempera- 5 color in the presence of various wetting and disture is then adjusted preferably between 70 C. persing agents. However, in spite of these atand 80 C. and an oxidizing agent is added. After tempts it has been found that these precipitated complete oxidation of the indoxyl, which can be pigments are rather coarse and therefore give carried out in numerous ways familiar to those rough and dull results when applied by dyeing or skilled in the art, the dye is isolated by filtration printing processes. Attempts have also been and washed free from salts and other soluble 20 made to achieve improved pigment dispersion of materials including the naphthalene sulfonic acid these colors by mechanical means such as vigorsalts. The resulting crude color is preferably ous milling and disintegration. One difficulty in standardized by the addition of water and printusing such mechanical means is the expense since ing assistants, such for example as those de- 5 such milling and disintegrating operations are scribed in U. S. P. 2,024,973, 2,024,974 and very expensive. Attempts have also been made 2,024,975. Alternatively the crude color can be to improve the dyeing properties of these colors standardized as'a dry powder by the addition of by mixing the colors with various assistants saccharic substances, sulfated alcohols, and variwhich tended to give improved color strength on ous other wetting and dispersing agents.

the dyed textile materials. However, in spite of The oxidizing agents which are used include 30 the vast amount of research in this field it has polysulfide, ferricyanide, Sitol, etc. been found that many difiiculties, similar to The invention may be more readily understood those mentioned above, are still present. by a consideration of the following examples.

It is an object of the present invention to prewmple 1 pare indigoid colors of superior dyeing and print- 35 ing strength. A further object is to produce indi- 100 parts of Y D goid colors in a finely divided and highly diswas suspended in 8,500 parts of water containing persed condition especially suitable for the print- 250 parts of sodium hydroxide and 10 parts of the ing of rayon. A still further object is to produce sodium salt of isopropylated naphthalene sulfonic indigoid colors of superior covering power when acid. This mixture was heated to a temperature 40 used as pigments. Additional objects will beof 70 C. and 300 parts of sodium polysulfide come apparent from a consideration of the fol- (NazS4.5) as a 40% 50 W added- Ihe red lowing description and claims. dye was completely precipitated after stirring at These objects are attained according to the the above temperature for approximately two herein described invention which broadly comhours. It was removed by filtration and washed 45 prises oxidizing an indoxyl in the presence of alkali-free with water. The resulting color cake, naphthalene sulfonic acid either as the free acid which weighed approximately 700 parts was or its alkali salt. mixed with a small amount of water and 7.5 parts In a more restricted sense the invention comof anthraquinone beta sodium sulfonate. In

prises dissolving or suspendingathioindoxyl in an order to obtain a thin workable paste a small 50 alkali solution under which condition the alkali amount of the reaction product of formaldehyde salt of the thioindoxyl is formed which may or and naphthalene sulfonic acid was added. This may not be completely soluble. To this mixcolor paste (20 parts) was mixed with printing ture is added alkylated naphthalene sulfonic acid gum (80 parts) and the resulting printing paste either as the free acid or its alkali salt. The was printed on rayon materials. The resulting print was stronger, brighter and smoother than a similar print prepared from color which was manufactured in an exactly similar manner but without the addition of the isopropylated naphthalene sodium sulfonate to the indoxyl solution. The printing gum referred to here contained approximately 12% sodium formaldehyde sulfoxylate, 17% potassium carbonate and glycerine along with suflicient thickeners to give the desired viscosity.

Example 2 100 parts of 7-methyl-5 chlor-thionaphthene was suspended in 8,000 parts of water containing 240 parts of NaOH and parts of isopropylated naphthalene sodium sulfonate. This solution was adjusted to a temperature of 70 C. and 300 parts of sodium polysulfide (Na2S4.s) Was added. The bluish red dye which began forming immediately was completely precipitated after two hours. It was removed by filtration and finally washed with water. It was standardized to a paste in a manner analogous to that described in Example 1. This color paste gave very superior results, stronger, brighter and smoother prints when printed on rayon than an exactly similar composition prepared from color precipitated in the absence of the isopropylated naphthalene sodium sulfonate.

Example 3 In a similar way 6:6'-dichlor-thioindigo was prepared by the oxidation of 6-chlor-thionaphthene in the presence of isopropylated naphthalene sodium sulfonate. 7

Example 4 In a similar way a dyestuif paste was prepared from 6:6'-diethoxy-thioindigo by oxidation of an alkaline solution of fi-ethoxy-thionaphthene in the presence of isopropylated naphthalene sodium sulfonate.

Example 5 In a similar way a dyestufl paste was prepared of 5 5-dichlor,-4:4'-7 7 '-dimethyl-thioindigo obtained by oxidizing an alkaline solution of 5- chlor-4z'l-dimethyl-thionaphthene in the presence of isopropylated naphthene sodium sulfonate.

Example 6 Example No. 1 was repeated except that butylated naphthalene sodium sulfonate was substituted for the isopropylated naphthalene sodium sulfonate in the indoxyl solution before oxidation. When this color was used for printing rayon materials the shades obtained .were stronger, brighter and smoother than those obtained from color precipitated in an exactly similar way but in the absence of butylated naphthalene sodium sulfonate.

It is to be understood that the aforementioned examples are representative only of the methods of practising the invention. These methods may be subjected to variations and modifications. Thus, this invention can be applied to any of the thioindoxyls which can be precipitated by the oxidation of their indoxyl solution. It can likewise be applied to the corresponding vats of the respective colors but such a use is not preferred for this class of colors since it involves an extra operation and the yields on the vatting operation are generally unsatisfactory. This invention can also be applied to any alkaline solution which upon oxidation will give an insoluble thioindigo.

However, the invention is preferably applied to the manufacture of Sulfanthrene Pink FF by oxidation in the presence of Alkanol B.

The amount of naphthalene sulfonic acid salt which is added will vary but generally an amount between 0.1 gram and 100 grams per 1000 cc. and preferably about 1 gram per 1000 cc. is sufiicient to obtain the advantageous results.

The alkalinity and temperature also will vary widely. Usually between about 0.5% and 10% caustic soda is sufficient alkalinity. The temperature will vary, depending on the oxidizing agent used as well as the indoxyl. Generally a temperature between 50 C. and 100 C. and preferably between 70 C. and 80 C. is sufiicient.

Colors precipitated in the presence of the aforementioned salts and acids are in a very much finer crystal size than those precipitated in its absence. Therefore, it is possible to prepare by means of this invention dyestufi pastes and powders containing very finely divided colors without having to resort to expensive milling and disintegrating operations. By this method it is possible to prepare colors of very high tinctorial value as pigments. Colors prepared in this way are especially suitable for the pigmentation of wallpaper and similar uses which do not depend upon fixation of the dyestuff by a preliminary reduction to its leuco. Furthermore, in textile printing operations these finely precipitated pigments give especially smooth and clear prints when applied by the usual methods of textile printing. This is particularly desirable in the printing of rayon fabrics especially of the pigmented rayon type.

As many apparently widely different embodiments of this invention may be made without departing from the scope and spirit thereof, it is to be understood that the invention is not limited to the specific embodiments except as defined in the appended claims.

Having described the present invention the following is claimed as new and useful:

1. A process for producing a thioindigo of high tinctorial value which comprises oxidizing a thio-' indoxyl compound in the presence of an isopropyl naphthalene alkali sulfonate. V

2. A process for producing a thioindigo of high tinctorial value which comprises oxidizing a thioindoxyl compound in the presence of isopropylated naphthalene sodium sulfonate.

3. A process for producing a thioindigo of high tinctorial value which comprises oxidizing an aqueous alkaline suspension of 4-methyl-6-chlorthionaphthene in the presence of the sodium salt of isopropylated naphthalene sulfonic acid.

4. A process for producing a thioindigo of high tinctorial value which comprises oxidizing a thioindoxyl compound in the presence of butylated naphthalene alkali sulfonate.

5. A process for producing a thioindigo of high tinctorial value which comprises oxidizing a thioindoxyl compound in the presence of butylated naphthalene sodium sulfonate.

6. A process for producing a thioindigo of high tinctorial value which comprises oxidizing a thioindoxyl compound in the presence of a member selected. fromvthe group consisting of isopropyl naphthalene alkali sulfonates and butyl naphthalene alkali sulfonates.

7. A process for producing a thioindigo of high tinctorial value which comprises suspending a thioindoxyl compound in an alkali solution, adding thereto between 0.1 gram and about,100 grams per 1000 cc. of solution of an lsooronvl naphthalene alkali sulfonate, and thereafter oxidizing at a temperature between 50 C. and 100 C.

8. A process for producing a thioindigo of high thioindoxyl compound in an alkali solution, adding thereto between 0.1 gram and about 100 grams per 1000 cc. of solution of a butylated naphthalene alkali sulfonate, and thereafter oxidizing at a temperature between 50 C. and 100 C.

JOHN ELTON COLE. 

